Short-term variations in pelagic photosynthesis demand well-timed sampling to monitor long-term limnological changes in Lake Victoria

Oxygen concentration and water transparency at two offshore stations in Lake Victoria varied significantly during a few hours around noon. This affects comparative limnological research on changes in oxygenation after a period of perturbation. Most of the recently published papers on this subject do not account for sampling time, whereas our data show the importance of well-timed sampling programmes. This revised version was published online in July 2006 with corrections to the Cover Date.